The present invention relates, in general, to display modules and, in particular, to a method and apparatus for improving continuity between a substrate and a display assembly.
Without limiting the scope of the invention, its background is described in connection with display modules used in mobile phones.
Typically in Liquid Crystal Display (LCD) devices a contact is made between a conductive pad located on an LCD and electrodes located on an LCD driver. For example, a semiconductor device, such as a Printed Circuit Board (PCB), uses a conductive elastomer interconnect. A steel frame is used to adhere the LCD and the LCD driver in a position that allows for minimum resistance between the conductive pad and the electrodes through the conductive elastomer interconnect. Variations in the position of the LCD and the LCD driver may create a discontinuity resulting in an increase in resistance across the conductive path. An increase in resistance across the conductive path affects the quality of the display.
Reference is now made to FIG. 1, where a prior art display module is illustrated and denoted generally as 10. Display module 10 comprises a substrate 12 having a electrode pad 14 comprising multiple electrodes 16 and a display assembly 18 having a conductive pad 20. A conductive elastomer 22 is positioned between electrode pad 14 and conductive pad 20. A steel frame 24 is used to secure substrate 12 to display assembly 18 and to maintain the integrity of the electrical connection between electrode pad 14 and conductive pad 20.
Substrate 12 is an electronic component, for example, a Printed Circuit Board (PCB), used to drive display assembly 18. Substrate 12 comprises electrode pad 14 having several electrodes 16 for receiving and transmitting electrical signals. Electrodes 16 may be formed from copper, gold-nickel plated copper or other similar materials. Display assembly 18, which may be an LCD for displaying visual information, includes conductive pad 20 formed of a transparent conductive film such as Indium-Tin Oxide (ITO). Conductive elastomer 22 is a flexible material comprising a plurality of flexible conductive wires. Conductive elastomer 22 interposed between electrode pad 14 and conductive pad 20 creates a conductive path between display assembly 18 and substrate 12.
The manufacture of steel frame 24 allows for a minimal y-axis variation. Variations in the steel frames y-axis may create a discontinuity or increase resistance across the conductive path formed by electrode pad 14, conductive pad 20 and conductive elastomer 22. Product use, for example, as a result of typical wear and tear, may also increase y-axis variations causing a further decrease in the quality of the electrical connection. In order to maintain a strong connection between electrode pad 14 and conductive pad 20, steel frame 24 must maintain a compression between 10% to 30% of elastomer 22.
As may be seen, therefore, an improved apparatus that eliminates y-axis variation in a display module used in mobile phones could provide a commercially useful article and improve the quality of the display module.
The present invention presents a display module exhibiting improved continuity between a conductive pad located on a display assembly and an electrode pad located on a substrate.
A display module is presented comprising a display assembly having a first side for displaying visual information and a second side. The second side comprises a first area having an adhesive layer and a second area having a through connection to a conductive pad. The display module further comprises a substrate having a first side for receiving the display assembly, wherein the first side comprises a first surface area for bonding to the adhesive layer and a second surface area comprising an electrode pad having multiple electrodes for receiving electrical signals. The display module further comprises a conductive elastomer positioned within the through connection. The conductive elastomer establishes conductive continuity between the conductive pad and the electrode pad when the display assembly is bonded to the substrate.